OBJECTIVE: To determine the prevalence of prostatitis on histopathological evaluation of prostatic tissue in men without urinary retention. DESIGN, SETTING AND SUBJECTS: The clinical data and histopathology reports of men seen from January 1999 through March 2009 at our institution were analysed using Student's t-test, the Mann-Whitney test and Fisher's exact test where appropriate. Values were expressed as means, medians and ranges (p<0.05 accepted as statistically significant). OUTCOME MEASURES: Data collected included patient age, duration of lower urinary tract symptoms and hospitalisation, findings on digital rectal examination, prostate volume, haemoglobin concentration, serum creatinine and prostate-specific antigen (PSA) levels, and histological findings. RESULTS: Prostatic tissue of 385 men without urinary retention at presentation was obtained via biopsy (48.3% of cases), transurethral prostatectomy (62.9%), retropubic prostatectomy (6.8%) or radical prostatectomy (28.3%). On histological examination, benign prostatic hyperplasia (BPH) was found to be present in 213 patients (55.3%) and adenocarcinoma of the prostate (ACP) in 172 (44.7%). Histological prostatitis was present in 130 patients (61.0%) with BPH and 51 (29.7%) with ACP (p<0.001). A previous study of 405 men presenting with urinary retention at our institution showed histological prostatitis in 98/204 (48.0%) with BPH and in 51/201 (25.4%) with ACP. The group of men with BPH alone had a significantly lower mean serum PSA at presentation (4.5 ng/ml, range 0.3 - 20.8 ng/ml) compared with the group with BPH and prostatitis (11.2 ng/ml, range 0.2 - 145 ng/ml, p=0.011). The mean PSA level at presentation did not differ significantly between the group with ACP only (40.9 ng/ml, range 0 - 255 ng/ml) and the group with ACP plus prostatitis (1 672 ng/ml, range 0.3 - 38 169 ng/ml, p=0.076). CONCLUSIONS: Among men presenting without urinary retention, histological prostatitis was significantly more prevalent in those with BPH than in those with ACP (61% v. 30%), similar to the previous study of men presenting with retention at our institution, in which histological prostatitis was significantly more prevalent in BPH than in ACP (48% v. 25%). This finding suggests that histological prostatitis is not significantly associated with the causation of ACP or urinary retention. Serum PSA at presentation was significantly higher in the group with BPH plus prostatitis compared with BPH alone, but not in the group with ACP plus prostatitis compared with ACP alone.